Hi friends, 
I would like to construct a matrix of seasonal dummies with number of rows (observations)=100. such matrix is written as follows:[1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1;1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1;etc...] . I wrote the following program:
T=100
br=matrix(0,T,4)
{
for (i in 1:T)
for (j in 1:4)
if i==j
br[i,j]=1 
if else (abs(i-j)%%4==0
br[i,j]=1
else 
br[i,j]=0
}
z<-br
z 

but unfortunately I obtained from the console the following message:
> {
+ for (i in 1:T)
+      for (j in 1:4)
+         (if i==j)
Erreur : syntax error, unexpected SYMBOL, expecting '(' dans :
"
"
>             br[i,j]=1
Erreur dans br[i, j] = 1 : objet "i" non trouvé
> 
>         (if else (abs(i-j)%%4==0)
Erreur : syntax error, unexpected ELSE, expecting '(' dans "        (if else"
>             br[i,j]=1
Erreur dans br[i, j] = 1 : objet "i" non trouvé
>         else 
Erreur : syntax error, unexpected ELSE dans "        else"
>             br[i,j]=0
Erreur dans br[i, j] = 0 : objet "i" non trouvé
>               }
Erreur : syntax error, unexpected '}' dans "              }"
>  
Can you please rectify my smal program, I tried to rectify it but I can't. Many thanks in advance.     
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